Local guys were using them when I moved to Indiana back in '84. That's as far back as I remember seeing them. There's a factory here that makes them. I've seen a lot of strange clamps on 2 cycles over the years as well -- some better than others.
Funny how prices come down on some things. Often times it has something to do with the country of origin.
I've personally never had a problem with the aluminum pinch clamps, but I've seen several of them laying on the track or had to have that "talk" with racers in the tech barn post-race.
No matter what clamp a guy uses, it still needs to be checked and safety wired.
OK Ok Ok I give.
I started using the "T" bolt version on all my engines when the Animal first hit the race track because they were better than the aluminum clamps.
My goodness i think that was 1999.
Now i use the other type that doesn't have the threaded stud sticking out.
I think they are more safe.